--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/src/lib/TransactionalBuffer.h Sat Jul 24 17:35:27 2021 +0200
@@ -0,0 +1,139 @@
+/**
+ * Relational pipes
+ * Copyright © 2021 František Kučera (Frantovo.cz, GlobalCode.info)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+#pragma once
+
+#include <string>
+#include <exception>
+#include <cstring>
+
+#include "AbstractParser.h"
+
+namespace relpipe {
+namespace in {
+namespace asn1 {
+namespace lib {
+
+class TransactionalBuffer {
+private:
+ uint8_t* buffer;
+ size_t bufferSize;
+ bool hasData = false;
+ size_t writePosition = 0;
+ // size_t writePositionCommited = 0; // TODO: transactions also on the writing side?
+ size_t readPosition = 0;
+ size_t readPositionCommited = 0;
+
+ size_t bytesRead = 0;
+ size_t bytesReadCommited = 0;
+
+ size_t availableForReading() {
+ if (readPosition < writePosition) return writePosition - readPosition;
+ else if (readPosition > writePosition) return bufferSize - readPosition + writePosition;
+ else if (hasData) return bufferSize;
+ else return 0;
+ }
+
+ size_t availableForWriting() {
+ if (readPositionCommited < writePosition) return bufferSize - writePosition + readPositionCommited;
+ else if (readPositionCommited > writePosition) return readPositionCommited - writePosition;
+ else if (hasData) return 0;
+ else return bufferSize;
+ }
+
+public:
+
+ /**
+ * Is thrown from read() and peak() methods if there are not enough data.
+ * Interrupts current update() cycle and causes rollback.
+ */
+ class ReadBufferUnderflowException {
+ // TODO: common super-class for exceptions, hidden implementation
+ };
+
+ /**
+ * Is thrown from write() method of the buffer when there is not enough space.
+ * Interrupts whole process.
+ */
+ class WriteBufferOverflowException {
+ };
+
+ TransactionalBuffer(size_t initialSize = 4096) : bufferSize(initialSize) {
+ // TODO: initial size + resize + hard upper limit
+ buffer = (uint8_t*) malloc(bufferSize);
+ }
+
+ virtual ~TransactionalBuffer() {
+ free(buffer);
+ }
+
+ void write(const uint8_t* inputBuffer, const size_t length) {
+ if (length == 0) return;
+ if (length > availableForWriting()) throw WriteBufferOverflowException(); // TODO: optional resize
+
+ hasData = true;
+
+ const size_t a = std::min(length, bufferSize - writePosition);
+ const size_t b = length - a;
+
+ // TODO: map buffer twice in the memory in order to create a continuous area and avoid the second memcpy()?
+ memcpy(buffer + writePosition, inputBuffer, a);
+ memcpy(buffer, inputBuffer + a, b);
+
+ writePosition = (writePosition + length) % bufferSize;
+ }
+
+ void read(uint8_t* outputBuffer, const size_t length) {
+ if (length == 0) return;
+
+ peek(outputBuffer, length);
+ readPosition = (readPosition + length) % bufferSize;
+ hasData = readPosition != writePosition;
+ bytesRead += length;
+ }
+
+ void peek(uint8_t* outputBuffer, const size_t length) {
+ if (length == 0) return;
+ if (length > availableForReading()) throw ReadBufferUnderflowException();
+
+ const size_t a = std::min(length, bufferSize - readPosition);
+ const size_t b = length - a;
+
+ memcpy(outputBuffer, buffer + readPosition, a);
+ memcpy(outputBuffer + a, buffer, b);
+ }
+
+ void commitRead() {
+ readPositionCommited = readPosition;
+ bytesReadCommited = bytesRead;
+ }
+
+ void rollbackRead() {
+ readPosition = readPositionCommited;
+ bytesRead = bytesReadCommited;
+ }
+
+ size_t getBytesRead() {
+ return bytesRead;
+ }
+
+};
+
+
+}
+}
+}
+}